Nicola Perry of Contagion Live writes that according to new research, applying antimicrobial coatings to whole cantaloupes during storage significantly reduces contamination by pathogenic bacteria, and has the potential to improve their microbiological safety and extend their shelf life.

Qiumin Ma, PhD, from the University of Tennessee in Knoxville, and colleagues published the results of their study in the International Journal of Food Microbiology.   Chitosan-based coatings “significantly inhibited the growth of E[scherichia] coli O157:H7, L[isteria] monocytogenes and S[almonella] enterica cocktails on whole cantaloupes during 14-day storage at ambient temperature (21°C),” the authors write. “Coatings also significantly reduced total mold and yeast counts on whole cantaloupes.”   Cantaloupes are particularly susceptible to microbial contamination because they grow on the ground and can therefore come into contact with foodborne-pathogens associated with polluted irrigation water, uncomposted manure, or animal droppings. They can also become contaminated during harvesting, handling, and preparation. The rough cantaloupe skin also allows bacteria to easily attach to the surface of the fruit. 

“These pre- and post-harvest safety factors have directly or indirectly contributed to more than 25 outbreaks of foodborne illnesses associated with the consumption of cantaloupes between 1973 and 2003 in the United States and Canada,” the authors state.  

Food preservation, safety, and quality maintenance therefore represent mounting concerns for the food industry. Antimicrobial food coatings represent just one form of technology that has been investigated as a tool to help improve food safety in various food types, including fresh produce and meats.    

Chitosan, derived from the polysaccharide chitin, is known to have film-forming properties as well as antimicrobial activity. Chitosan-based coatings have also been shown to improve food safety—in fresh produce, for example.   With this in mind, Dr. Ma and colleagues conducted a study to investigate the efficacy of such antimicrobial coatings in reducing bacterial populations from the surface of cantaloupes. In addition to chitosan, they investigated two generally-recognized-as-safe antimicrobials—lauric arginate (LAE; which inhibits a broad spectrum of foodborne pathogens) and cinnamon oil (CO; an essential oil that has shown activity against Listeria species, gram negative bacteria, E. coli 0157:H7, and Salmonella species). They also investigated ethylenediaminetetraacetic acid (EDTA; an agent that chelates divalent calcium ions that are important to bacterial structures; it also enhances the activity of some antimicrobials).